ECE 101 Exploring Electrical Engineering

MATLAB

• General Features

• Videos

• User Interface

• Expressions

• Data Types

P.K. Wong and B. Pejcinovic

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MATLAB is a technical computing program created by The Mathworks, Inc. (http://www.mathworks.com)

Features:

Includes many operators and built-in functions

Supports both numeric and symbolic solutions

Operates on scalars, vectors, and matrices

Can generate 2D and 3D graphs

Extendable by add-ons and scripting (user programs)

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For introduction to MATLAB use watch the following videos available at

http://www.mathworks.com/products/matlab/videos.html

MATLAB overview (has cc):

http://www.mathworks.com/videos/matlab-overview-61923.html

Getting started (no cc):

http://www.mathworks.com/videos/getting-started-with-matlab-68985.html

Working in development environment (optional, no cc)

http://www.mathworks.com/videos/working-in-the-development-environment-69021.html

Get help (no cc):

http://www.mathworks.com/videos/top-ways-to-get-help-89848.html

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For introduction to MATLAB – use tutorials from Mathworks:http://www.mathworks.com/academia/student_center/tutorials/mltutorial_launchpad.html

In particular: MATLAB Onramp. Question: is it available to all students or just those who purchased student version? Check. One problem – no cc but there is no voice / video – just assignments using online Matlab

Section 4.2 is video with no cc – this is on import tool; I may not need this … 4.1 is OK (just save and load)https://matlabacademy.mathworks.com/R2015b/portal.html?course=gettingstarted#chapter=4&lesson=2&section=1

It looks decent …

Could start here https://matlabacademy.mathworks.com/R2015b/

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For introduction to MATLAB – use tutorials from Mathworks:

5 – indexing into and modifying arrays – not really needed …

6 – array calculations – not needed

7 – calling functions – not needed

8.1 – video on help

9 – plotting vectors; 9.3 is video; nice but a bit much for 101 – needs cc

10 – project on plotting; don’t use it. It’s good for 102!

11 – Matlab editor 11.1 is video (no cc); this would be good for HW assignment … https://matlabacademy.mathworks.com/R2015b/portal.html?course=gettingstarted#chapter=11&lesson=1&section=1

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MATLAB User Interface (R2015a)

Current FolderShows files in the current folder (i.e., directory)

Command Window• Used for entering

commands• Displays calculated

results and messages

WorkspaceShows values of variables

Command HistoryRecords a history of all entered commands

RibbonUI commands

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Hide or unhide ribbon

Back Forward Up OneLevel

Browsefor folder

Current folder name/path

Ribbon tabsCut/Copy/Paste

Save to fileUndo/Redo

Help (F1)

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Editor WindowUsed for creating and debugging scripts and programs

(this separate window appears when a new script is created or an existing script is opened)

Figure WindowDisplays graphs generated by plot commands

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Command Window Notes

Definition → A “command” is:

an instruction that causes some action to occur

a mathematical expression that is evaluated

Command prompt is: >>

To interact with the Command Window:

Type a command at the prompt line and press the Enter key.

Use the ↑ (up-arrow) key and the ↓ (down-arrow) key to recall previously typed commands.

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Entering a command automatically displays its associated output value (if any).

Example:>>

x =

2048

>>

Appending a semicolon ( ; ) at the end of a command will usually suppress the output.

Example:>> x = 2 * 1024;

>>

Command: multiply 1024 by 2 and save the result in variable x

Output: current value of x

x = 2 * 1024

Notice the semicolon at the end of this command

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Commonly used commands:

Command Purpose

clc Clears the command window

help name Displays help information about a givencommand or function

lookfor key Searches for and displays all commands related to a given keyword

quit Shuts down and exits the MATLAB programAlternatives:Menu bar option: File→Exit MATLABKeyboard shortcut: Ctrl+Q

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Expressions

Expressions are any valid combination of numbers, operators, functions, and variables.

MATLAB can be used as a calculator by directly typing expressions in the command window.

Predefined values:Name Description

pi

inf

i or j

NaN

The number InfinityDefined as √-1 Not-A-Number

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Standard Data Types

Real numeric

Example: 1 5.23 -83.5 1.25e3

Use e for scientific notation (e.g., 3.1×10-2 → 3.1e-2)

Imaginary numeric

Example: i 2i -3.5i 5e2j

MATLAB accepts both i and j for imaginary

Complex numeric

Example: 1+i 5.23+2i -83.5-3.5i

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Character – single text letter, number, or symbol

Example: 'A' 'z' '3' '$'

Use a pair of single quotes to define a character.

Note: The numeric value 3 is not the same as the character value '3'.

Each character is associated with a unique numeric code. This is the collating sequence.

String – collection of one or more characters

Example: 'x' 'MATLAB' 'rooms 4 rent!'

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Examples of commands and functions you will use in ECE 101:

Generate a vector with angles from 0 to 90 degrees, in increments of 10 degrees:

x = [ 0, 10, 20, 30, 40, 50, 60, 70, 80, 90]

Find sin of series of values stored in a

vector

Y = sind(x)

Note: sin() operates on angles in

radians while sind() operates on

angles in degrees

Other trig functions: cos, cosd, tan,

tand and inverses.

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Examples of commands and functions you will use in ECE 101:

Generate a vector with values from 0 to 10 degrees, in increments of 1:

x = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Find exponent e^{x} of series of values

stored in a vector

z = exp(x)

Find a natural log of z

Zlog = log(z)

Find a log10 (logarithm with base 10)

Zlog = log10(z)